1. Field of the Invention
This invention relates to a device for compensating a shake caused by hand-held use on photographing in an optical device such as a camera, which refers to a silver halide film camera, a digital camera, a TV camera, a camcorder, or a gastrocamera.
2. Description of the Related Art
Conventional devices for compensating a shake caused by hand-held use on photographing in an optical apparatus such as a camera are available in those in which a variable angle prism placed in front of a photographic lens is used (for example, Japanese Patent Kokai No. Hei 5-181094) and those in which a reflecting mirror placed in front of the photographic lens is used (for example, Japanese Patent Kokai No. Hei 4-211230).
A shake compensating device disclosed in Kokai No. Hei 4-211230 is constructed with a mirror and a mirror supporting mechanism in which the mirror is supported, in front of the photographic lens of a camera, to be tiltable, at an angle of about 45° as a center, with respect to the optical axis of the photographic lens. The device includes the mirror supporting mechanism comprised of a chassis which is fixed at angle of about 45° with the optical axis of the photographic lens in front thereof, a ball interposed between the reverse side of the mirror and the chassis, and spring members pressing the mirror against the chassis with resiliency through the ball; a mirror driving means for tilting the mirror; a shake sensor for detecting the shake of the camera; and a control means for controlling the mirror driving means so that light from an object incident on the photographic side of the camera is stabilized in accordance with the detecting output of the shake sensor.
The mirror driving means has two piezoelectric elements which change a space between the chassis and the mirror. The two piezoelectric elements are two bimorph cells, which are arranged, like cantilevers, parallel with the chassis and perpendicular to each other. The mirror driving means has two power transmitting means driven by the top portions of the two bimorph cells, and the two power transmitting means are arranged at the positions of two bottom angles of a right-angle isosceles triangle, with a center of the ball at a vertex. Moreover, the two power transmitting means are constructed so that power transmitting reference points relative to the mirror practically coincide on a plane parallel with the mirror through the center of the ball.
However, the device using the variable angle prism has the problem that since a ray of light transmitted through the prism is conducted to the photographic lens, image quality is easily deteriorated due to chromatic aberration.
The shake compensating device disclosed in Kokai No. Hie 4-211230 is such that since the displacement of the bimorph cell is mechanically transmitted to the mirror to control the tilt of the mirror, a mechanical mechanism is easily complicated and compensation for large shake is difficult because the amount of displacement is relatively small. Furthermore, the bimorph cell has a hysterisis characteristic, and thus feedback control is required. This brings about complicated control and slow response time. In this publication, it is suggested that a voice coil is used as an actuator, but in this case also, the same defect as in the bimorph cell cannot be obviated.